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package org.spongycastle.openpgp.operator.bc;
import org.spongycastle.crypto.AsymmetricBlockCipher;
import org.spongycastle.crypto.BlockCipher;
import org.spongycastle.crypto.BufferedAsymmetricBlockCipher;
import org.spongycastle.crypto.InvalidCipherTextException;
import org.spongycastle.crypto.params.AsymmetricKeyParameter;
import org.spongycastle.crypto.params.ElGamalPrivateKeyParameters;
import org.spongycastle.openpgp.PGPException;
import org.spongycastle.openpgp.PGPPrivateKey;
import org.spongycastle.openpgp.PGPPublicKey;
import org.spongycastle.openpgp.operator.PGPDataDecryptor;
import org.spongycastle.openpgp.operator.PublicKeyDataDecryptorFactory;
/**
* A decryptor factory for handling public key decryption operations.
*/
public class BcPublicKeyDataDecryptorFactory
implements PublicKeyDataDecryptorFactory
{
private BcPGPKeyConverter keyConverter = new BcPGPKeyConverter();
private PGPPrivateKey privKey;
public BcPublicKeyDataDecryptorFactory(PGPPrivateKey privKey)
{
this.privKey = privKey;
}
public byte[] recoverSessionData(int keyAlgorithm, byte[][] secKeyData)
throws PGPException
{
try
{
AsymmetricBlockCipher c = BcImplProvider.createPublicKeyCipher(keyAlgorithm);
AsymmetricKeyParameter key = keyConverter.getPrivateKey(privKey);
BufferedAsymmetricBlockCipher c1 = new BufferedAsymmetricBlockCipher(c);
c1.init(false, key);
if (keyAlgorithm == PGPPublicKey.RSA_ENCRYPT
|| keyAlgorithm == PGPPublicKey.RSA_GENERAL)
{
byte[] bi = secKeyData[0];
c1.processBytes(bi, 2, bi.length - 2);
}
else
{
BcPGPKeyConverter converter = new BcPGPKeyConverter();
ElGamalPrivateKeyParameters parms = (ElGamalPrivateKeyParameters) converter.getPrivateKey(privKey);
int size = (parms.getParameters().getP().bitLength() + 7) / 8;
byte[] tmp = new byte[size];
byte[] bi = secKeyData[0]; // encoded MPI
if (bi.length - 2 > size) // leading Zero? Shouldn't happen but...
{
c1.processBytes(bi, 3, bi.length - 3);
}
else
{
System.arraycopy(bi, 2, tmp, tmp.length - (bi.length - 2), bi.length - 2);
c1.processBytes(tmp, 0, tmp.length);
}
bi = secKeyData[1]; // encoded MPI
for (int i = 0; i != tmp.length; i++)
{
tmp[i] = 0;
}
if (bi.length - 2 > size) // leading Zero? Shouldn't happen but...
{
c1.processBytes(bi, 3, bi.length - 3);
}
else
{
System.arraycopy(bi, 2, tmp, tmp.length - (bi.length - 2), bi.length - 2);
c1.processBytes(tmp, 0, tmp.length);
}
}
return c1.doFinal();
}
catch (InvalidCipherTextException e)
{
throw new PGPException("exception encrypting session info: " + e.getMessage(), e);
}
}
public PGPDataDecryptor createDataDecryptor(boolean withIntegrityPacket, int encAlgorithm, byte[] key)
throws PGPException
{
BlockCipher engine = BcImplProvider.createBlockCipher(encAlgorithm);
return BcUtil.createDataDecryptor(withIntegrityPacket, engine, key);
}
}
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